At the single photon level, the photon that goes into the polarizer and the photon that goes out of the polarizer are not the same photon, so it's not right to

At the single photon level, the photon that goes into the polarizer and the photon that goes out of the polarizer are not the same photon, so it's not right to say that a photon is changed or transformed. For a photon coming in at 45 degrees to the polarization angle, the probability that another photon will be emitted is sin(45deg) =~ 70% and the probability that it will be absorbed is 1/sin(45deg) =~ 30%. (This is also a simplification; polarization angle is similarly quantum in nature, and I have assumed it to be collapsed here)